Color filter (CF) for liquid crystal display (LCD), which comprises black matrix and red, green and blue color pixels on a glass substrate, is manufactured by photolithography using radically photopolymerizable resists. After the photolithographic process, post-baking by heating for example at 230° C. for 30 min is normally performed to polymerize remaining acrylic double bonds to attain required durability in the production process of CF/LCD and for long-term survival in LCD as permanent coat. In the market there is a strong demand for lower temperature and/or shorter time in the post-baking process for following reasons:    1) use of thermally less stable but inexpensive soda-lime glass as substrate for cost reduction,    2) reduction of energy consumption,    3) shorter tact time for higher productivity and/or    4) more freedom in choice of materials for CF.
Low temperature curing might be required for other resists and curing compositions used for manufacturing of Displays besides color filter resists.
Resist makers have attempted to attain low temperature curing CF resist by use of existing thermal radical initiators like peroxides.
JP10010718 discloses a color former, which includes organic peroxides as thermal polymerization initiators and production of a color filter having good solvent resistance by applying post-baking process, preferably at 100-180° C., after photolithography process.
JP2003330184 discloses a colored photosensitive resin composition capable of forming a color filter having high heat resistance, high hardness and high solvent resistance even after the resin composition is subjected to heat treatment of comparatively low temperature. The resin is composed of a polymerization initiator having an oxadiazole structure or a triazine structure containing a trihalomethyl group.
JP2003128957 provides a curable composition for forming a protective film capable of providing the protective film having various excellent physical properties even when the protective film is formed at a temperature not higher than the deformation temperature or discoloration temperature of a resin substrate. This curable composition comprises (A) a copolymer of (a1) an unsaturated carboxylic acid and/or an unsaturated carboxylic acid anhydride, (a2) an epoxy group-containing unsaturated compound and (a3) an olefinically unsaturated compound other than the monomers (a1) and (a2), (B) an epoxy resin other than the component (A) and (C) a compound capable of producing an acid with heat or radiations. The protective film is formed from the curable composition; The method for forming the protective film comprises coating the top surface of the resin substrate with the curable composition and then carrying out heat and/or light treatment. The treatment is carried out at a temperature without exceeding 180° C.
JPA2003015288 discloses a radiation sensitive composition, including thermal polymerization initiators like organic peroxides, hydroperoxide and azo compounds, capable of forming a color filter having satisfactory adhesion to a plastics substrate even if such low temperature treatment as not to cause deformation or yellowing to the plastics substrate is adopted when the color filter is formed on the plastics substrate and to provide a color filter formed form the composition. The radiation sensitive composition contains (A) a colorant, (B) an alkali-soluble resin, (C) a polyfunctional monomer, (D) a photopolymerization initiator and (E) a thermal polymerization initiator.
The European patent EP309400 (Ciba) describes N-acyloxy hindered amine stabilizers to stabilize an ambient curable or acid catalyzed thermosetting coating composition.
Hydroxylamine esters are known as thermal initiators to polymerize ethylenically unsaturated monomers.
The International Publication WO2001090113 (Ciba) describes polymerizable compositions comprising hydroxylamine esters and an ethylenically unsaturated monomer or oligomer.
The International Publication WO03029332 (Ciba) relates to a process for crosslinking unsaturated polymer resins as e.g. unsaturated polyesters using hydroxylamine esters as radical source.
The International Publication WO04081100 (Ciba) relates to a dual thermal and ultraviolet radiation curable coating composition, comprising at least an ethylenically unsaturated compound and a hydroxylamine ester as thermal initiator.
The international Publication WO2006027327 (Ciba) relates to the degradation of polypropylene with hydroxylamine ester compositions.
It has been found that the use of hydroxylamine esters as disclosed in WO2006027327 as thermal radical initiators for radically polymerizable compositions used to manufacture color filters results in a sufficiently high C═C conversion surprisingly at lower temperature and/or in shorter time in the thermal curing (post baking) process which takes place after the photo curing process both in comparison to corresponding compositions lacking these hydroxylamine esters and in comparison to corresponding compositions comprising other thermal radical initiators (TRIs), e.g. peroxides, than these hydroxylamine esters.